Backfiring biometrics

I’ve written on a number of occasions about the fallibility of biometrics as a trusted means to find or identify an individual. Setting aside problems with the mathematics of biometrics and associated false accept / false reject issues, my biggest concern is the human factor: once the authorities have it into their heads that biometrics never lie, common sense and good judgement go out the window. This is particularly important where biometric evidence is used in a police investigation, since it becomes impossible for defendants to challenge either the accuracy of the original evidence, or of the procedures used to process it within the investigation. High-profile false convictions become inevitable, and it would only take a few such cases to completely undermine the evidential value of biometrics even in apparently ‘open and shut’ cases.

Perhaps the most important example of this in the UK is that of Shirley McKie, a police officer whose fingerprint was allegedly discovered at the scene of a murder in 1997. Despite the absence of motive or any other evidence, she was brought to trial and eventually cleared of perjury when she defended her innocence of involvement in the crime. Four supposed experts asserted that the print had to be hers, and in the wake of her trial three accepted redundancy and one was sacked. Mrs McKie, having left the police service, was subsequently awarded £750,000 in compensation, and one of the experts was eventually reinstated having successfully challenged her dismissal at an employment tribunal. HM Chief Inspector of Constabulary demanded an overhaul of procedures, and a public inquiry is now under way.

Aside from the ridiculous waste of public funds in pursuing a patently unsafe conviction, the most disturbing aspect of the case is the way in which police and justice authorities closed ranks to protect their own staff and their unswerving faith in biometric evidence. The Scottish Information Commissioner Kevin Dunion has ordered that 131 previously unreleased documents about the case be provided to Mrs McKie. Whilst only a fraction of the 630 documents yet to be disclosed (and likely to remain secret because of other legal exemptions), this demonstrates just how hard it is for an individual to fight a case once there is a claim of infallible biometric evidence against them.

I very much hope that Mrs McKie is successful in exposing every flaw that lead to this ridiculous situation, and that authorities across the UK – not just in Scotland – take heed of the lessons learned and modify their attitudes towards biometric evidence accordingly.